X s slide-valve



(ModeL) Q S. TRETHEWEY.

, Slide Valve. v v NO. 240,286. Patented April 19,1881.

- UNITED STATES PATENT GFFICE.

SAMUEL TRETHEWEY, OF PITTSBURG, PENNSYLVANIA.

SLI DE-VALV E.

SPECIFICATION forming part of Letters Patent No. 240,286, dated April19, 1881.

Application filed January 28, 1881.

its ports and passages, and a tubular slidevalve, the same beingillustrative of my inven-' tion. Fig. 2 is a transverse sectional viewof the steam chest and valve, taken in the plane of the line w :12,Fig. 1. Fig. 3 is an enlarged view, partly in section and partly inelevation, of my improved valve. Fig. at is a transverse sectional viewof the valve, taken in the line y y, Fig. 3; and Fig. 5 is a sectionalview of a detached portion of the valve, taken in the .line 2 2, Fig. 4.

My invention relates to certain improvements in steam-engineslide-valves; and, in general terms, it consists in making such valve oftubular form, having a shell divided longitudinally, so as to expandunderinternal pressure, with steam-ports in the shell arranged toregister with passages in the steam-chest leading to the supply-pipe,and also with passages to both ends of the cylinder, whereby theinterior of the valve constitutes a part of the steam-supply passage,the ends of such shell being closed and its length divided, ashereinafter described, and,further, in combining such valve with achamber adapted in form to hold the parts of the valve together while inuse.

In the drawings, A A represent parts of a steam-engine cylinder andpiston. B is the steam-chest; a, a, steam-passages leading from thechest to either end of the cylinder. b b are exhaust-ports. O is thesteam-supply pipe, leading, by branch passages U, to annular passages orchambers 00, which surround and open into the valve-chamber H. Theseparts, exceptas hereinafter described,may be of any desired form adaptedto co-operate with my improved valve, which is arranged, constructed,and operated as follows:v

(ModeL) The body of the valve is formed of a tubular shell, E, which isdivided longitudinally into two parts, as at 6, Fig. 3. The two ends ofthis divided shell are closed by heads iand i, which are connected, bystems or rods F F, with a central distance piece or disks, f f, whichlatter serves as a diaphragm to divide the interior of the shelltransversely, and also affords means for securing the valve to the stem,as presently described. This distancepiece ff is made of two separatedisks, which are cast or rigidly secured to the separate parts of thedivided shell, one to each. By overlapping, as shown, such disks effectthe desired separation between the parts of the interior, and also allowadjustment or motion of the shell, as required.

The head i, which closes the upper end of the shell E, is secured to onedisk, f, of the distance-piece by a rod, F, the head being secured onone end of the rod in any convenient way, as by nut m and collar m,while the inner end of the rod is screwed or otherwise fastened into thedisk. The other head, t", is secured on the stem F, either by nut andcollar, or, as shown, by means of a conical enlargement, at, on the stemfitting a correspondinglyshaped hole through the head, the taper of suchenlargement holding the head in one direction, and a key, a, holdingitfrom moving in the opposite'direction. The inner end of stem F isscrewed into the disk f of the central distance-piece, and thus makesattachment with the valve. The heads '5 and t are packed or madeexpansible, so as to fill the ends of the shell by means of elastic orspring bands 1", whichare seated in grooves r, sunk in the peripheriesof the heads. These bands are cut or open, and the joint thus made isbroken by lapping projections 'r (See Fig. 3, at bottom.) When in placethe bands are under compression, and by their tendency to expand theynot only close the space between the peripheries of the heads and theshell, but also tend to press the parts of the shell against the wallsof the valve-chamber H, and thereby prevent leakage either through oraround the ends of the valve.

In order to close passage through the openings e at the ends, and alsoto prevent one part of the shell from slipping longitudinally on theother part, gluts s are inserted in openings s, made in the shell,across the line 0, at either end. These gluts conform in outline to thesurfaces of the shell. They are by preference made to fit tightly in oneside or part of the openings 8', and a dovetail fitting may be employedfor this purpose, if desired; also, the side edges of the gluts may befitted to the edges of the openings by A-shaped grooves and projections,as at .9 Fig. 5. But in any case it is desirable to provide for somemotion of the glut in one part of the shell or opening, so as to allowexpansion. This may be done by the means shown and stillthe joint bemade practically steam-tight. The gluts being of the same thickness asthe shell and arranged in the planes of the heads i i, as shown, thebands 7' will press them against the inclosingwall of the valve-chamberalong with the shell.

The valve-chamber H is bored round and true, and the outer surface ofthe shell is similarly fitted, so as to fit closely within the chamberand bear against its walls through its length and circumference, exceptwhere openings are made in either for steam-passages. While thusinclosed the parts of the valve cannot become separated, and yet theyare free to such extent as to permit the shell to expand under internalpressure.

Near the outer ends of the shell are made ports h and h in any desirednumber, which in the travel of the valve register alternately with thepassages a 0/. Also, near the center of the shell, on either side of thedistance-piece 3 5 ff, are made ports 70 and 7c in any desired number,which are so arranged with relation to the ports h h and passages c cthat when the ports at either end register with the passages a or a, asthe case may be, the ports or k on the same side shall also registerwith the annular supply-passages c or 0. As shown in Fig. 1, the ports hregister with a, and the ports k on the same side register with passage0. On the other side of the distance-piece the ports hand k are closedby the chamber-wall, and are out of communication with both a and 0. Insuch construction steam is admitted to the cylinder from the steam-pipethrough the valve, which thus forms a part of the steampassage.

The exhaust-ports b and b lead from the valve-chamber outside of orbeyond the passages aa, so that the end of the valve closes the exhaustas soon as it enters that part of the chamber, as shown atthe lower endof Fig. 1, and in such position the bands 1" serve to press or expandthe end of the valve-shell against the inclosing-Wall, and thereby packthe same or prevent leaking, as above described.

Any desired lap may be provided by properly arranging the position andwidth of the ports and passages.

It will be observed that as the valve moves to open the exhaust theports h or h are closed before the exhaust is opened, and as a resultboth parts or ends of the valve are at all times, when in operation,filled with steam at nearly equal pressure, giving practically equalpressure of steam on the shell through its length and also thedistance-pieceff is balanced by pressure on opposite sides, andconsequently no great accuracy is required in fitting such parts. Thissteam-pressure within the valveshellis employed to secure one of theprincipal objects of my inventi0nthat is, to press or expand somewhatthe valve-shell against the walls of the chamber, and thereby pack thevalve, and also enlarge it as the valve and chamber wear by use, so asto fill or fit properly. To this end the shell is made of properthickness and material to yield under the usual pressure of steamemployed. Also, the longitudinal division of the shell is made withspecial reference to this end, and renders my improved valveself-compensating for wear to a greater extent than is true of'otliervalves of this class of which I have knowledge.

Instead of dividing the shell into two separate parts, a single slit, 0,may be-made therein from end to end, so that the shell may open underpressure, though, for convenience of construction, I prefer to make theshell in separate parts, as shown and described. Owing to the greatextent of surface-bearing between the shell and its inclosing-wall, thepressure of the shell thereon is not an impediment to the proper workingof the valve, but, on the contrary, prevents leakage between suchsurfaces by an operation equivalent to automatic packing.

I have designed my improved valve more especially for use insteam-hammers, and have found by use that it is well adapted therefor,and is free from several objections which have attended the use ofpiston and other valves, such as bounding, wearing, and leaking. Myimprovement is well adapted for other use in steam-engines, however, andI do not wish to limit its application to hammers and similar uses.

The valve-stem F may be packed, as at D, in any suitable way, andsuitable or well-known means are to be employed for operating the valveand for fitting the parts of the engine.

I claim herein as my invention- 1. An expansible slide-valve having atubular shell divided longitudinally, with expanding heads for closingthe ends of the shell, a two-part (listance-piece,ff, and inlet andoutlet ports in the shell on both sides of, the distance-piece,substantially as described.

2. A tubular slide-valve having, in combination, a longitudinallydividedshell, heads 11 i, elastic bands 1, gluts 8, arranged in the planes ofthe bands across the line of division between the parts of the shell,distancepiece f f, and inlet and outlet ports in the shell on both sidesof the distance-piece, substantially as set forth.

3. A tubular expansible slide-valve having a cylindrical shell, E,divided longitudinally into separate parts, with gluts s, expansibleheads for closing the ends of such shell, and arranged to register withthe ports of the valve, two-part distance-piece arranged centrallysubstantially as set forth. 10

across the interior of the shell, with inlet and In testimony whereof Ihave hereunto set outlet ports in the shell on both sides of the myhand.

5 distance-piece, in combination with steam-chest SAMUEL TRETHEWEY.

B, having valve-chamber H therein, adapted Witnesses: in form and sizeto hold the parts of the valve R. H. WHITTLESEY,

together, and having steam-passages a a a c, G. L. PARKER,

